Allow chips with attribution to always expand

Chips with attribution text should always be expanded, regardless of
their position on the list. They won't necessarily be the last.

Bug: 403422950
Flag: com.android.systemui.enable_underlay
Test: atest NavBarPillScreenshotTest
Change-Id: Ib70d3af49f33dbc0596baee5c47ea35c39663ecd